Treadless lamp and base



Nov. 11, 1969 R. M. GRIFFIN 3,478,300

THREADLESS LAMP AND BASE Filed March 20, 1967 ROBERT M. GRIFFIN INVENTOR ATTORN EY Unitcd States Patent 3,478,300 TREADLESS LAMP AND BASE Robert M. Grilfiu, South Hamilton, Mass, assignor to Sylvania Electric Products Inc., a corporation of Delaware I Filed Mar. 20, 1967, Ser. No. 624,295 Int. Cl. H01r 33/02, 33/20 US. Cl. 339-72 Claims ABSTRACT OF THE DISCLOSURE Field of the invention This invention relates to incandescent lamps and specifically to the bases of such lamps and more particularly to lamp bases for incandescent lamps which are to be quickly disconnected.

Description of prior art With the exception of special applications most of the incandescent lamps utilize a threaded baseand socket arrangement. The threaded bases as well as their mating sockets are standardized so that regardless of the number of lamp manufacturers involved, the bases will be interchangeable with one another. Various lamp specifications call for different size base" and sockets but these too have standardized threads and are I interchangeable throughout the industry. In certain fields, the use of the threaded base'becomes a time consuming and sometimes awkward procedure, especially when large numbers of lamps have to be maintained. One very important area is in the illuminated'advcrtising sign or lighted display fields, where a larger number of incandescent lamps are used, and where frequent maintenance is required. Needless time and energy is expended with the use of the conventional thread and socket arrangement especially when it has been determined that it requires 4 to 5 hand twisting motions to propertly seat one screw base lamp. When these motions are multiplied by the number of lamps used, it can bacome a time-consuming task to maintain large area lamp displays.

Summary of the invention To overcome this decided drawback, I provide a threadless base, having a number of outwardly extending fingers arranged annularly around the periphery of the base. These resilient fingers are formed as equally spaced cuts made into a cup-shaped shell that is fixed to the bottom of a two-step threadless lamp base shell. The cuts are made longitudinal and parallel to the axis of symmetry of the base shell, which will then define a series of fingers. Each finger is twisted outwardly in a predetermined orientation about its longitudinal axis to form a diameter that is slightly larger than the root diameter of the mating socket. The motion required to seat the lamp into a socket is a straight push along the axis of the symmetry of the lamp. This straight-line push compresses the resilient fingers enough to allow the base to be inserted into the socket in one motion. In an inserted position, the base contact button of the lamp will be in electrical contact with a centrally located electrical socket tab of the socket "ice and the resilient fingers try to expand to their maximum diameter. Because of ditference of pitch of the threads to that of the top of the finger some of the finger tops will engage and hold to the slope of the sockets threads while the remaining fingers are held tightly compressed. These compressed fingers are held firmly by the higher crest portion of the socket threads, and the base is thereby firmly locked in a positive electrical relationship within the socket. Removal of the threadless base from the socket is almost a reverse operation to that of insertion with the exception that a slight twist is necessary to compress the resilient fingers so that the lamp may be pulled from the socket in one straight axial pull. The slight twist is in the same direction of the orignal pre-set twist, and brings all of the fingers opposite a crest of the thread where they are compressed to their smallest diameter.

Description of drawings FIG. 1 is an elevational view of an electric lamp embodying the threadless base.

FIG. 2 is an enlarged cross-sectional view of the lamp base taken on lines 2-2 of FIG. 1.

FIG. 3 is an enlarged detail view of the invention shown in the seated position in a conventional electrical socket.

Description of the preferred embodiment Reference is now made to FIGS. 1 through 3 of the drawings wherein the threadless base, embodying the invention, is shown comprising the base of a conventional incandescent lamp. The base 10 comprises a two-stepped shell 12 the lower half having a recessed diameter, a resilient finger cup 14, a conventional cone of insulating material 16 and a contact button 18. The basic shell 12 is generally cup-shaped and axially symmetrical having an open end with a flared edge portion 20 shaped to receive the base portion of a glass envelope 22. The lower reduced half of the shell 12 provides an area for the adaptation of the resilient finger cup 14 that can be brazed or welded to the lower portion of the shell 12.

A conventional lamp envelope 22 such as shown in FIG. 1 is fitted to the base shell 10 in a conventional manner and usually includes an exhaust tube and a pair of filament lead-in wires (not shown) that extend below the neck of the lamp envelope. The shell 12 encompasses the exhaust tube and the lead-in wires, both lead wires being directed within the shell 12 for electrical circuitry for the lamp, one wire being Welded to the internal side of the base shell 12 and the other to the centrally located contact button 18 spaced from the shell 12 by the insulated cone 16.

Referring to the drawings, the resilient finger cup 14 is made by forming a number of equally spaced cuts parallel to the axis of symmetry of the cup to define a series of fingers 24. Each finger 24 is cut to an equal depth and then twisted, in this particular case, clockwise or counter-clockwise about their longitudinal axis. This twisting offsets the upper edges of the fingers to describe a diameter that is slightly larger than the root diameter of a conventional mating socket. The twisted finger configuration of this cup 14 can more clearly be seen in FIG. 2. After fabrication of cup 14, it is secured to the bottom of the shell 12 by welding or brazing, or some other suitable means (such as staking, press fit, or shrinkfit) so that it becomes an integral part of the base shell 12. A mating pair of holes 13 are provided in the base shell 10 and the cup 14. These holes and a hole 15 in the insulated cone 16 provide access to the contact button 18, fitted to the lower part of insulated cone 16. One of the lead-in wires passes through the mating holes 13 through hole 15 in the cone-shaped insulator material 16 to the contact button 18 where it is welded in place. This completes the electrical circuitry of the lamp.

In reference to FIG. 3 the completed threadless base sealed to an incandescent lamp envelope 22 is shown seated in a conventional lamp socket 28, where the contact button 18 of threadless base 10, it is in contact with a conventional electrical tab 30 of the socket 28. The socket shown is of the conventional type better known as an Edison-type screw shell which thread form is comprised of two circular segments of approximately equal radii and tangent to each other. A lamp having a base of this type can be inserted into a socket with a straight line push, whereby the resilient twisted fingers 24 being of a slightly larger diameter than the crest of the socket thread are compressed to a diameter of the shell 12. When properly seated, the contact button 18 will be in electrical engagement with the tab 30, and the resilient fingers 24 will than expand to their full diameter.

In reference to FIG. 3 the top of the fingers 24lie in a perpendicular plane to the axis of the lamp, whereas the standard threads 27 of the socket 28 have a slight pitch which results in the top ends of some of the fingers 24 contacting and biting into the sloping wall of threads of the socket. It can be noted that the remaining fingers that are not held in this captive position but compressed in varying degrees by the crest 36 of the sloping threads of the socket 28. The removal of the base from the socket is a simple procedure. As noted above the resilient fingers 24 are formed by twisting in a counter-clockwise direction therefore with same directional motion of the base the fingers held captive by the slope of the threads will become depressed by gradually moving the top of the fingers to the crest of the threads. With this slight twisting it can be seen that all of the resilient fingers can be depressed to a diameter that is smaller or equal to that of the base shell. Therefore the lamp can be removed from the socket with one straight axial pull.

It may be mentioned at this time that the use of this particular resilient arrangement shown and described has proven to be the most economical method of construction. But many various combinations can be utilized, such as the slotted fingers can be cut into the base shell of circular shell or a ring of fingers can be added to the shell. I have found that by utilizing a resilient cup member such as shown and described in my invention I have overcome most of the objectives found in the fabrication and utility of the lamp.

What I claim is:

' 1. A lamp connector comprising: a symmetrical reduced stepped base shell, a cup having a rim of resilient 4 fingers, an insulated separator and a metal contact button; said resilient fingers being equally spaced about the periphery of said reduced step, and twisted to define an enlarged diameter greater than the diameter of said base shell; said fingers and said base shell being insulated from said metal contact button by said insulator separator; said resilient fingers providing a holding means for said base shell when inserted into an Edison type socket shell.

2. In an incandescent lamp the improvement which comprises: a symmetrically stepped base shell, a cup having a rim of resilient fingers, an insulated separator and an electrical contact button; said resilient fingeres of said cup are formed in equal length cuts made parallel to the axis of symmetry to the base and said fingers are twisted to form an enlarged diameter equal to or greater than said base, said resilient finger cup is afiixed to the reduced stepped portion of said base and separated from said contact button by said insulation separator, said base is afiixed to said lamp envelope to form a threadless base lamp.

3. A base for an incandescent lamp comprising: a symmetrically stepped base shell; an annular cup having a rim of resilient fingers, said cup being affixed to and disposed about the lower portion of said base shell; an insulated separator disposed at the lower portion of said base shell and within the annulus of said cup; an electrical contact button disposed upon said insulated sepator and insulated from said base shell.

4. The base according to claim 3 wherein the resilient fingers of the cup are formed by a plurality of cuts of equal size and space, parallel to the axis of symmetry of the cup, said fingers being twisted to enlarge the diameter.

5. The base according to claim 4 where the length of the resilient fingers formed in the cup by the cuts is less than the length of the reduced portion of the base shell whereby the enlarged diameter of the cup can be depressed to a diameter which is smaller or equal to the diameter of said base shell.

References Cited UNITED STATES PATENTS 1,761,344 6/1930 Huber 33972 2,004,550 6/1935 Bradley 339-72 3,056,941 10/1962 Eriksson 33972 3,215,972 11/1965 Eriksson 33972 RICHARD E. MOORE, Primary Examiner US. Cl. X.R, 339 

